Maintaining write ordering in a system

• US 20070233947A1
• Filed: 03/30/2006
• Published: 10/04/2007
• Est. Priority Date: 03/30/2006
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Coulson, Richard, Trika, Sanjeev, Matthews, Jeanna, Faber, Robert
• Granted Patent: US 7,640,395 B2
• Time in Patent Office: Days
• US Class Current: 711/113
• CPC Class Codes: G06F 12/0804 with main memory updating G06F12/0806 takes precedence
• CPC Class Codes: G06F 12/0866 for peripheral storage systems, e.g. disk cache
• CPC Class Codes: G06F 12/0891 using clearing, invalidating or resetting means

Abstract

In one embodiment, the present invention includes a method for maintaining a sequence of writes into a disk cache, where the writes correspond to disk write requests stored in the disk cache, and ordering cache writes from the disk cache to a disk drive according to the sequence of writes. In this way, write ordering from an operating system to a disk subsystem is maintained. Other embodiments are described and claimed.

Claims

1. A method comprising:

storing a sequence of writes into a disk cache, the writes corresponding to disk write requests stored in the disk cache; and

ordering cache writes from the disk cache to a disk drive associated with the disk cache according to an order of the sequence of writes maintained in the disk cache.

2. The method of claim 1, further comprising:

determining whether to insert data of a disk write request into the disk cache; and

flushing dirty data from the disk cache to the disk drive if the data of the disk write request is not to be inserted into the disk cache.

3. The method of claim 1, further comprising flushing dirty data from the disk cache to the disk drive at a predetermined time interval.

4. The method of claim 1, further comprising:

determining whether the disk drive has been used in a system not including the disk cache; and

resetting the disk cache if the determination indicates the disk drive usage.

5. The method of claim 4, wherein the determining whether the disk drive has been used further comprises obtaining a count associated with the disk drive.

6. The method of claim 1, further comprising storing a sequence number corresponding to each write of the sequence of writes in the disk cache with metadata associated with the write.

7. The method of claim 1, further comprising writing streaming data into the disk cache based on a cost of flushing dirty data in the disk cache.

8. An article comprising a machine-accessible medium including instructions that when executed cause a system to:

insert data of a disk write request into a memory coupled to a disk drive; and

write a sequence number in the memory corresponding to the disk write request.

9. The article of claim 8, further comprising instructions that when executed cause the system to:

increment the sequence number;

insert data of a second disk write request into the memory; and

write the incremented sequence number in the memory corresponding to the second disk write request.

10. The article of claim 8, further comprising instructions that when executed cause the system to prevent execution of write operations directly from an operating system to the disk drive until dirty data in the memory has been written to the disk drive.

11. The article of claim 10, further comprising instructions that when executed cause the system to flush the dirty data in the memory to the disk drive in an order in which the dirty data was inserted into the memory.

12. The article of claim 8, further comprising instructions that when executed cause the system to reset the memory if the disk drive was used outside of the system, wherein the memory comprises a non-volatile memory.

13. The article of claim 8, further comprising instructions that when executed cause the system to write dirty data in the memory to the disk drive at a selected time interval.

14. The article of claim 13, further comprising instructions that when executed cause the system to obtain the selected time interval from a user of the system.

15. An apparatus comprising:

a non-volatile memory to store data of write requests, the data in the non-volatile memory to be written to a disk drive in a write order corresponding to storage of the write requests in the non-volatile memory.

16. The apparatus of claim 15, wherein the non-volatile memory is to store a sequence number associated with each write request.

17. The apparatus of claim 15, wherein the disk drive is separable from a first system including the non-volatile memory and usable in a second system.

18. The apparatus of claim 17, further comprising a controller to reset the non-volatile memory if the disk drive is used in the second system and returned to the first system.

19. The apparatus of claim 15, wherein the non-volatile memory comprises a controller to flush dirty data in the non-volatile memory before direct transfer of data from an operating system to the disk drive is permitted.

20. The apparatus of claim 15, further comprising a controller to flush dirty data in the non-volatile memory to the disk drive at a fixed interval.

21. The apparatus of claim 15, wherein the non-volatile memory comprises a memory array that is to include a plurality of entries each to store data of a write request and a corresponding sequence number to indicate an order in which the plurality of entries are to be written to the disk drive from the non-volatile memory.

22. The apparatus of claim 21, further comprising a controller to recover logical to physical mapping of data based on the sequence number.

23. A system comprising:

a processor to execute instructions of an operating system;

a mass storage device; and

a memory coupled between the mass storage device and the processor to cache data, the memory to store sequence information associated with each write request from the operating system to the mass storage device that is stored in the memory.

24. The system of claim 23, wherein data of each write request is to be sent from the memory to the mass storage device in an order according to the sequence information.

25. The system of claim 23, wherein the memory further comprises a controller to flush dirty data from the memory to the mass storage device at a fixed time interval.

26. The system of claim 23, wherein the mass storage device is separable from the system and usable in a second system, wherein the memory comprises a non-volatile memory affixed to the system.

27. The system of claim 26, further comprising a controller to clear contents of the non-volatile memory if the mass storage device is used in the second system and returned to the system.

28. The system of claim 23, wherein the memory comprises a memory array that is to include a plurality of entries each to store data of a write request with corresponding sequence information.

29. The system of claim 28, wherein the memory further comprises a storage for an ordering list, the ordering list to indicate an order in which the plurality of entries are to be written to the mass storage device from the memory.

30. The system of claim 28, further comprising a controller to recover data in the memory on a power failure based at least in part on the sequence information.